Mask and etch processes are commonly used during the manufacture of semiconductor wafers for integrated circuits. A patterned resist mask is applied to the surface of a layer of material to be etched. An etch process (e.g., a plasma etch) is then applied. The portions of the patterned resist mask that cover the surface of the material prevent the material from being etched when an etch process is applied. The openings through the patterned resist mask allow the etch process to etch the underlying material that is exposed to the etch process. After the etch process is completed the pattered resist mask is removed.
The depth to which the underlying material is etched is determined by the controlling the amount of time that the material is exposed to the etch process. The rate at which the etch process etches the material is known or can be estimated. An etch process that is time controlled is referred to as a timed etch. In a timed etch the etch process is terminated after a predetermined amount of time has elapsed.
It would be advantageous to have a system and method for controlling an etch process for a semiconductor material that is more accurate and precise than a timed etch. There is a need in the art for a system and method that is capable of terminating an etch process of a semiconductor material at a precisely located depth in the etched material.